The present invention relates generally to non-linear electronic devices, such as non-linear capacitors. More specifically, but not exclusively, the present invention relates to an electronic device integrated on a semiconductor substrate, with the electronic device being integrated or used in association with a circuit network including non-linear devices.
Data detection for transmission channels is based on the use of a network of non-linear devices, as readily understood by those skilled in the art. Data detection with non-linear devices is becoming more popular because of the simplicity of the circuit networks, including such non-linear devices, and because of a corresponding lower production cost.
A circuit network including non-liner devices requires that the non-linearity of such devices be well controlled and follow a well-defined rule. Once these conditions are met, then the resulting network provides some advantages in data detection when compared with other more complex approaches.
The devices used in this kind of network are usually capacitors and inductors that have a non-linear relation between capacitance and voltage for the capacitors, and a non-linear relation between inductance and current for the inductors. One of the main difficulties for manufacturing an integrated circuit network including non-linear devices is that the non-linear components are to be provided as discrete elements. An integrated non-linear capacitor or inductor is hard to form based upon current technology.
For instance, U.S. Pat. No. 6,166,604 relates to a semiconductor amplifier including a distortion compensation circuit. The disclosed amplifier comprises a non-linear amplifying element connected to an integrated capacitor that prevents a direct current from flowing through a passive circuit. The integrated capacitor is formed in a known manner.
Up to now, there have not been any straightforward approaches for easily integrating an electronic circuit that includes non-linear passive components. Consequently, there is a need for implementing non-linear passive devices into a semiconductor electronic circuit, thus allowing the construction of a network of non-linear devices for data detection in transmission channels.
The scope of the present invention is to provide a method for integrating a non-linear passive device, such as a non-linear capacitor, and to provide a corresponding circuit.
More specifically, the present invention may provide a non-linear capacitor with the following relationship:   C  =            C      0        ·          1              1        -                  k          ·                      V            c            2                              
The present invention is based on the fact that non-linear passive devices are formed by using active components connected in a feedback loop for emulating the same behavior of the non-linear passive device. In other words, the present invention utilizes active devices operating in a feedback loop to implement the function of a non-linear capacitor.
Other objects, features, and advantages of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration only and various modifications may naturally be performed without deviating from the present invention.